support Socks5Proxy config

[kaidiren]

tor has been blocked in china. if you want to use tor, you should have Socks5Proxy at first

[j01tz]

Will look into options for specifying a pluggable transport/proxy for tor in grin-wallet for users located where tor is censored. We might not be able to provide the proxy server info from the wallet itself but we should be able to allow a user to add something like:

grin-wallet listen --bridge obfs4 [IP:PORT] [KEY] cert=[CERT] iat-mode=0

where the user provides the proxy information and the torrc config is updated accordingly for both listen and send commands.

The challenge for the user will be to obtain the information of an unblocked bridge out-of-band. For best success you will need to obtain private obfs4 proxies that have not been published or shared publicly. A determined user can always run their own private obfs4 proxy.

Actually it might be possible to do already today by doing the following:

1. Set up your own private obfs4proxy bridge by following https://community.torproject.org/relay/setup/bridge/
   1.5 Alternatively, obtain a bridge from https://bridges.torproject.org/bridges?transport=obfs4 (some of these may not work in all countries as they have already been published, but if you cannot find any that work, see step 1)
2. Have grin-wallet generate torrc files for listener and sender by running the commands once
3. Add the following line to the end of .grin/main/tor/listener/torrc and .grin/main/tor/sender/torrc:

bridge obfs4 [IP:PORT] [KEY] cert=[CERT] iat-mode=0

Example line:

bridge obfs4 176.58.114.86:62124 A9CFB9134869FA01AEC11A7457353DE185309B09 cert=/iARNee4ifcX4FtzAfkubkCnaVUuAqDZpswKM8OOz/sTkxKdmnE/x7imqAppzXAdJfq+Ow iat-mode=0

Have not tested the above but it might be a quick fix until a proper --bridge flag can be added to grin-wallet.

Edit: just tested and above and unfortunately it does not work because the file is overwritten when the command is run again. It looks like it would require some changes in grin-wallet to work.